1. Field of the Invention
This invention resides in the field of bearings for high-speed rotary machinery, and fluid bearings in particular.
2. Description of the Prior Art
Bearings are a critical part of any rotary machinery, particularly when such machinery is operated at high speed and high pressure. Many types of machinery are designed for operation under these conditions, ranging from industrial rotary equipment to aircraft, including turbopumps and propulsion and injection systems. The average consumer may be most familiar with rolling element bearings, but these are unsuitable for high-speed and high-pressure machinery due to the speed and load capacity limitations of a typical rolling element bearing and the wear that such a bearing suffers during extended use. The bearings that are used are therefore fluid bearings, both hydrodynamic and hydrostatic.
Hydrodynamic bearings rely on the dynamic effect of the rotor on the fluid. In rotary systems containing hydrodynamic bearings, the motion of the rotor itself draws the bearing fluid into the regions where the gap between the rotor and stator is the smallest and the friction therefore the greatest, and by drawing the fluid into these regions the bearing increases the pressure in these regions. Hydrostatic bearings supply fluid from an external pressurized source to designated regions of the gap, although these bearings often include withdrawal and recycling of the fluid as needed to adjust the pressure differentials and the position of the rotor. Unlike hydrodynamic bearings, the pressure exerted by a hydrostatic bearing is not dependent on the rotation of the rotor.
One of the factors in achieving and maintaining a long life cycle for high-speed rotary machinery is the balancing of the forces on the rotor. Transient loads present a special challenge to the design of the bearing, since balancing these loads requires a high degree of flexibility and rapid response time. Rotary machinery of the prior art typically lacks this flexibility.